/*
 * @lc app=leetcode.cn id=113 lang=cpp
 *
 * [113] 路径总和 II
 *
 * https://leetcode.cn/problems/path-sum-ii/description/
 *
 * algorithms
 * Medium (63.26%)
 * Likes:    1079
 * Dislikes: 0
 * Total Accepted:    387.1K
 * Total Submissions: 611.9K
 * Testcase Example:  '[5,4,8,11,null,13,4,7,2,null,null,5,1]\n22'
 *
 * 给你二叉树的根节点 root 和一个整数目标和 targetSum ，找出所有 从根节点到叶子节点 路径总和等于给定目标和的路径。
 * 
 * 叶子节点 是指没有子节点的节点。
 * 
 * 
 * 
 * 
 * 
 * 示例 1：
 * 
 * 
 * 输入：root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22
 * 输出：[[5,4,11,2],[5,8,4,5]]
 * 
 * 
 * 示例 2：
 * 
 * 
 * 输入：root = [1,2,3], targetSum = 5
 * 输出：[]
 * 
 * 
 * 示例 3：
 * 
 * 
 * 输入：root = [1,2], targetSum = 0
 * 输出：[]
 * 
 * 
 * 
 * 
 * 提示：
 * 
 * 
 * 树中节点总数在范围 [0, 5000] 内
 * -1000 
 * -1000 
 * 
 * 
 * 
 * 
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    void Traversal(vector<vector<int>>& results, TreeNode*node, vector<int>& path, int count, int Target) {
        if (node == nullptr)
            return;

        if (count + node->val == Target &&
            (node->left == nullptr && node->right == nullptr)) {
            //这里也要回
            path.push_back(node->val);
            results.push_back(path);
            path.pop_back();
            return;
        }

        //回溯
        path.push_back(node->val);
        Traversal(results, node->left, path, count + node->val, Target);
        path.pop_back();

        path.push_back(node->val);
        Traversal(results, node->right, path, count + node->val, Target);
        path.pop_back();
    }

    vector<vector<int>> pathSum(TreeNode* root, int targetSum) {
        if (root == nullptr)
            return {};

        vector<vector<int>> result;
        vector<int> path;
        Traversal(result, root, path, 0, targetSum);

        return result;
    }
};
// @lc code=end

